[CI/CD] Fix CI Python tests by using python -m pip (#1838)

- The CI pipeline was failing with "pip: command not found" error.
- Updated run_python_tests.sh to invoke pip through the Python
interpreter (python -m pip) instead of directly, ensuring compatibility
with ASWF CI containers where pip may not be directly in PATH.

**Link the Issue(s) this Pull Request is related to.**
- #1839

Author: ramonfigueiredo

ci/run_python_tests.sh

@@ -11,24 +11,24 @@ args=("$@")
 python_version=$(python -V 2>&1)
 echo "Will run tests using ${python_version}"
 
-pip uninstall --yes opencue_proto opencue_pycue opencue_pyoutline opencue_cueadmin opencue_cueman opencue_cuesubmit opencue_rqd
+python -m pip uninstall --yes opencue_proto opencue_pycue opencue_pyoutline opencue_cueadmin opencue_cueman opencue_cuesubmit opencue_rqd
 
 if [[ -v OPENCUE_PROTO_PACKAGE_PATH ]]
 then
   echo "Installing pre-built opencue_proto package"
-  pip install ${OPENCUE_PROTO_PACKAGE_PATH}
+  python -m pip install ${OPENCUE_PROTO_PACKAGE_PATH}
 else
-  pip install ./proto
+  python -m pip install ./proto
 fi
 
 for package in pycue pyoutline cueadmin cueman cuesubmit rqd
 do
   PACKAGE_PATH="OPENCUE_${package^^}_PACKAGE_PATH"
   if [[ -v "${PACKAGE_PATH}" ]]
   then
-    pip install "${!PACKAGE_PATH}[test]"
+    python -m pip install "${!PACKAGE_PATH}[test]"
   else
-    pip install "./${package}[test]"
+    python -m pip install "./${package}[test]"
   fi
   python -m pytest ${package}
 done